JP2010089887A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device without causing paper wrinkles and jam, even when carrying extra thin paper. <P>SOLUTION: A sheet sucking condition is changed by comparing a height difference in the uppermost sheet detected by a flapping detection sensor 71 for detecting a height difference in deformation generated in the uppermost sheet sucked by a sheet feeder, with an allowable height difference for properly carrying the sheet. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a printer or a copier that includes a sheet feeding device that feeds sheets one by one from a storage in which a plurality of sheets are stored.

  Conventionally, in this type of image forming apparatus, in order to feed sheets one by one from the sheet storage, gas (mainly air) is blown to the end of the sheet bundle, and a plurality of sheets are floated and separated to convey the sheets. An air sheet feeding device that adsorbs and conveys the belt has been proposed.

  An example of the air sheet feeding device will be described with reference to FIGS. In FIG. 12, the storage 11 includes a sheet base 12 on which a plurality of sheets are placed, a rear end regulating plate 13 that regulates the upstream (rear) side of the sheet conveyance direction, and a direction perpendicular to the conveyance direction (sheet width direction). It is composed of a side end regulating plate 14 that regulates. The rear end regulating plate 13 and the side end regulating plate 14 are configured so that the positions can be arbitrarily changed according to the size of the sheet.

  In FIG. 13, when the user pulls out the storage 11 along the slide rail 15, sets sheets, and stores the storage means in a predetermined position, the sheet base is raised in the direction A in the figure by the drive means (not shown). Begin to. Then, it stops at a position where the distance between the uppermost surface of the sheet and the suction conveyance belt 21 becomes B, and prepares for a feeding signal.

  In FIG. 14, when the feeding signal is detected, the separation fan 31 is operated, and air is sucked in the direction C in the figure, and the sheet is seen from the nozzle 33 and the separation nozzle 34 through the separation duct 32 from the directions D and E in the figure, respectively. Sprayed on the bundle 35. Then, a part of the sheet bundle 35A of the sheet bundle 35 floats. On the other hand, the suction fan 36 is operated, and air is discharged in the direction F in the figure. At this time, the suction shutter 37 is still closed.

  Further, in FIG. 15, when a predetermined time elapses after the feeding signal is detected and the floating of the sheet bundle 35A is stabilized, the suction shutter 37 is rotated in the direction G in the drawing. Then, a suction force in the H direction in the figure is generated from a suction hole (not shown) formed in the conveyance belt, and the uppermost sheet 35B of the sheet bundle 35A is adsorbed.

  Finally, in FIG. 16, the belt drive roller 41 is rotated in the J direction in the drawing, whereby the sheet 35B is conveyed in the K direction in the drawing, and the drawing roller pair 42 is rotated in the L and M directions in the drawing to To the transport path.

  Note that the separation nozzle 34 is provided to prevent so-called double feeding, in which two or more sheets are simultaneously conveyed during sheet conveyance. Only the uppermost sheet 35B is separated and conveyed by the air blown from the separation nozzle 34 to the tip of the sheet bundle 35A (see Patent Document 1).

Japanese Unexamined Patent Publication No. 7-196187

  By the way, since the sheet feeding device using air is suitable for high speed, it is often used for high-speed image forming devices, and the output products from the image forming device are catalogs, product instruction manuals, direct mails. Or it is used for various purposes such as publications.

  In recent years, in a high-speed image forming apparatus used for the above-mentioned applications, there is an increasing demand for feeding thin paper from various viewpoints in view of saving resources and reducing the transportation cost of products.

However, since the ultra-thin paper having a basis weight of 50 g / m ² or less is thin and not stiff, the sheet flutters by the air blown from the whirling nozzle 33 and the separation nozzle 34, thereby causing undulation. If the suction operation is performed when such a sheet is unstable, the sheet is adsorbed to the adsorbing and conveying belt 21 with the wave being undulated. Can not.

  If the sheet is conveyed by rotating the adsorption conveyance belt 21 while it is not uniformly adsorbed to the belt surface, the conveyance resistance in the conveyance guide increases, causing slippage between the drawing roller pair 42 and the sheet. And it becomes jammed. Further, the wavy is crushed by the pair of drawing rollers 42 and becomes a wrinkle state that does not return to the original state, so that it cannot be used as a product.

  The technical problem of the present invention has been made in view of the circumstances as described above, and an object thereof is to form an image with an air sheet feeding device that does not generate paper wrinkles or jams even when conveying ultra-thin paper. To provide an apparatus.

  In order to achieve the above object, a typical configuration according to the present invention includes sheet storage means for storing a sheet bundle, and air blowing means for blowing air to the sheet bundle stored in the sheet storage means, Generated in the uppermost sheet sucked by the sucking and conveying means in an image forming apparatus comprising: an sucking and conveying means that sucks and conveys air one by one from the uppermost sheet floated by the air blowing means A height difference detecting means for detecting a difference in height of the deformation, and comparing the height difference detected by the height difference detecting means with an allowable height difference for properly conveying the sheet; It is characterized by changing the adsorption conditions.

  According to the present invention, it is possible to prevent the occurrence of jamming and wrinkling due to the corrugation of the sheet, and to minimize the reduction in productivity caused thereby.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, with the same reference numerals given to the same constituent members as those of the conventional example. FIG. 1 is a schematic sectional view of an image forming apparatus provided with a sheet feeding apparatus according to an embodiment of the present invention. 2 is a schematic configuration diagram of the sheet feeding apparatus, FIG. 3 is a block diagram of the sheet feeding apparatus, and FIGS. 4A to 4C are sheet feeding when viewed from the direction of the arrow R in FIG. The stroke diagram of the feeder is shown.

  In the image forming apparatus shown in FIG. 1, the original is automatically sent to the reading position by the original conveying unit 120, and the image information is read by the image reading unit 130. The read image information is subjected to image processing, and laser light is emitted from the laser scanner unit 111 by a signal based on the processing result, and an electrostatic latent image is formed on the photosensitive drum 112.

  The electrostatic latent image on the photosensitive drum 112 is developed by the developing unit 113. Sheets such as paper and OHT stored in the storage 115 serving as a sheet storage means are fed by a sheet feeding device including a conveyance suction belt 21 and the like, and a toner image on the photosensitive drum 112 is registered with the registration unit 117. The image is transferred by the transfer unit 118 in synchronization. Then, the sheet is guided to the fixing roller pair 114, and is subjected to heat and pressure processing to be permanently fixed.

  In FIGS. 2 and 3, the storage 115 is composed of a sheet base 12, a rear end regulating plate 13, and the like, and the conveyance suction belt 21 is driven by a suction conveyance belt motor 63. As shown in FIG. 4A, the conveyance suction belt 21 includes three conveyance suction belt portions 60a, 60b, and 60c arranged in a direction orthogonal to the sheet conveyance direction. In addition, suction ports 54a, 54b, and 54c, which are suction portions, are formed inside the transport suction belt portions 60a, 60b, and 60c, respectively.

  An adsorption duct 70 is communicated with the adsorption ports 54a, 54b, 54c, and the adsorption duct 70 is connected to an adsorption fan 50. Further, suction shutters 51, 52, and 53 are individually provided rotatably at the suction ports 54a, 54b, and 54c. The suction solenoids 66, 67, and 68 rotate the suction shutters 51, 52, and 53, so that the suction ports 54a, 54b, and 54c are individually opened and closed. The suction conveyance means of the present invention is constituted by the conveyance suction belt 21, the suction conveyance belt motor 63, the suction duct 70 and the like.

  In addition, the sheet feeding device includes a paper surface detection sensor flag 58 for detecting the topmost sheet height and a suction completion for determining whether or not the topmost sheet (paper) is sucked to the transport suction belt 21. A sensor 55 is included.

  Two paper surface detection sensors 61 and 62 are provided in the vicinity of the paper surface detection sensor flag 58. The paper surface detection sensors 61 and 62 detect the height of the uppermost paper by being shielded by the shielding plate of the paper surface detection sensor flag 58, and the paper surface detection sensor 61 defines the lower limit boundary of the paper surface height that can be fed. Then, the paper surface detection sensor 62 detects the upper limit boundary of the paper surface height that can be fed.

  At a position facing one end of the conveyance suction belt 21, a undulation detection sensor 71 which is a height difference detecting means for detecting the degree of undulation of the adsorbed sheet is provided. The undulation detection sensor 71 is a CCD sensor that can acquire the undulation state of the adsorbed sheet edge as image data.

  The height difference of the corrugated deformation of the sheet is obtained from the image data acquired by the corrugation detection sensor 71, and the suction solenoids 66, 67, 68 are controlled in accordance with the appropriate opening timing of the suction shutters 51, 52, 53. To do.

  Further, an extraction sensor 56 is disposed on the downstream side of the conveyance adsorption belt 21 in the conveyance direction, and a pair of extraction rollers 57 is provided on the downstream side thereof.

  Next, the sheet feeding operation under a predetermined suction condition will be described. When the sheet table 12 is raised by the rotation of the lifter motor 65, the sheet bundle P set in the storage case 115 is raised accordingly. Then, the uppermost sheet of the sheet bundle P is detected by the paper surface detection sensor 61, and at the same time, the rising of the sheet table 12 is stopped.

  Next, when a feed signal from the controller 100 is detected, the firing (separation) fan 31 rotates and air is blown from the firing nozzle 33 and the separation nozzle 34 by air blowing means in the directions of arrows E and D in the figure, respectively. . As a result, the top several sheets of the sheet bundle P are lifted, and the sheet surface of the sheet bundle P is raised. At this time, when the paper surface detection sensor 62 is turned on, the lifter motor 65 is driven by the signal of the controller 100 that receives the signal from the paper surface detection sensor 62, and the sheet table 12 is lowered.

  Thereby, when the paper surface detection sensor 61 is turned on and the paper surface detection sensor 62 is turned off, the paper surface control is completed. Further, as shown in the operation timing chart of FIG. 6, the suction fan 50 rotates after a certain time from the start of the rotation of the separation fan 31.

  Next, when the paper surface control is completed after the rotation of the suction fan 50 is started, the suction solenoids 66, 67, and 68 are operated by a signal from the controller 100, and as shown in FIG. Is opened. Then, after a certain time (30 ms in this embodiment), the suction solenoids 66, 67, 68 operate, and the suction shutters 52, 53 on both sides are opened as shown in FIG.

  This suction shutter opening timing (hereinafter, referred to as a suction time difference) corresponds to a change in the wave size, and is optimized so as to have a wave size that does not cause wrinkles.

  When the suction shutters 51 to 53 are opened at the timing as described above, the suction force is generated in the direction of the arrow in FIG. 4B from the suction hole of the suction conveyance belt 60b by releasing the suction shutter 51. Next, a suction force is generated in the direction of the arrow in FIG. 4C from the suction holes of the suction conveyance belts 60a and 60c.

FIG. 5 shows the behavior of the sheet at this time. FIG. 5A shows a floating state when thin paper is floated by air from the rolling nozzle 33 and the separation nozzle 34, and is in a wavy state. If it is a thick sheet, it will not wave, but the ultra-thin paper with a basis weight of 50 g / cm ² or less is not affected by the turbulence generated by the sprinkling air and separation air. As shown in 5 (a), a wavy state is likely to occur and is not stable.

  When the suction shutter 51 is released from this state, a suction force is generated from the suction hole of the transport suction belt portion 60b. Therefore, as shown in FIG. 5B, the vicinity of the transport suction belt portion 60b is air-sucked. The Subsequently, when the suction shutters 52 and 53 are released, air is adsorbed in the vicinity of the conveyance suction belt portions 60a and 60c, and the air suction is completed with a small undulation as shown in FIG.

In the configuration of this embodiment, the time required for adsorbing ultrathin paper having a basis weight of 50 g / cm ² or less, that is, the section X in FIG. 6 is about 50 ms.

  Next, when the air suction is completed, the suction completion sensor 55 detects and sends a signal to the controller 100. Receiving the signal from the suction completion sensor 55, the controller 100 operates the suction conveyance belt motor 63 after a certain time (in this embodiment, 50 ms).

  When the suction conveyance belt motor 63 rotates, the conveyance suction belt 21 rotates in the J direction, and the sheets are conveyed one by one in the K direction. After the sheet is conveyed and the pulling sensor 56 is turned on, the sheet enters the pulling roller 57 that starts rotating.

  Next, when the trailing edge of the sheet passes through the suction completion sensor 55, the signal is sent to the controller 100, and as shown in FIG. To stop. Thereafter, the sheet is conveyed to the pair of drawing rollers 57 and sent out of the sheet feeding apparatus, and the feeding operation is completed. In FIG. 3, reference numeral 64 denotes a drawing motor that drives the drawing roller pair 57.

  Next, the operation for optimizing the undulation will be described in detail. FIG. 7 shows a graph obtained by performing binarization image processing on the image data acquired by the wave detection sensor 71 and extracting only the shape of the sheet edge. FIG. 7 is a graph when adsorption is performed without a difference in adsorption time (0 ms). The corrugation of the sheet is represented by the difference (height difference) between the maximum value and the minimum value of the corrugation indicated by H.

FIG. 8 shows the relationship between the height difference H in a high-temperature and high-humidity environment with a basis weight of 47 g / m ² and the occurrence rate of wrinkles when the sheet is conveyed in that state.

  Here, the maximum height difference that does not cause wrinkles and enables proper sheet conveyance is defined as an allowable height difference. Under these conditions, it can be seen that wrinkles do not occur when the height difference is 3 mm or less. Therefore, the allowable height difference H0 is 3 mm.

  In the case of FIG. 7, since the height difference H is 5 mm, it can be seen that wrinkles occur when the sheet is conveyed as it is. Since the allowable height difference varies depending on the paper type, basis weight, and environment, it is preferable to create an allowable height difference table according to these.

  FIG. 9 shows a wavy state when the adsorption time difference is 30 ms. Since the height difference H is 2 mm, which is less than the allowable height difference H0 (3 mm), wrinkles will not occur if the sheet is conveyed in this state.

  Since the effect of reducing the height difference due to such a difference in adsorption time also varies depending on the paper type, basis weight, and environment, it is preferable to prepare an appropriate adsorption time difference table accordingly.

  The operation procedure for optimizing the undulation will be described with reference to the flowcharts shown in FIGS. First, an appropriate adsorption time difference acquisition mode at the initial stage of sheet feeding will be described with reference to FIG.

  When the sheet feeding operation is started, an appropriate adsorption time difference tabled in advance as a database is acquired from the paper type, basis weight, and environmental information to be fed (steps S1 and S2), and sheet suction is performed by the time difference. (Step S3).

  Next, sheet suction is performed based on the appropriate suction time difference (step S3), and the height difference H is calculated from the image data of the undulation detection sensor 71 at this time (step S4).

  On the other hand, the above-mentioned database also includes an allowable height difference table for paper type, basis weight, and environmental information, and an allowable height difference H0 is also acquired from this database (step S5).

  Then, the height difference H and the allowable height difference H0 are compared (step S6). If H is equal to or less than H0 and the difference is equal to or less than 2 mm, the appropriate adsorption time difference set at this time is updated and the database is updated (step S7). This sheet is conveyed (step S8).

  If this sheet is not the final sheet (step S9), the process proceeds to the continuous feeding mode (A) shown in FIG. If H is less than H0 and the difference exceeds 2 mm, the appropriate suction time difference set at this time is judged to be too large and sheet suction is stopped (step S10), and the suction time is changed to be smaller. (Step S11), the sheet is sucked again (Step S3).

  This is because if the suction time difference is large, the sheet feeding time interval is correspondingly increased and the productivity is deteriorated, so that the suction time difference is not set more than necessary.

  In the present embodiment, the difference between H and H0 is 2 mm as a criterion for changing the suction time, but the present invention is not limited to this. This value also varies depending on the paper type, basis weight, and environmental information.

  If H is greater than H0, wrinkling may occur if the sheet is conveyed as it is, so sheet suction is stopped (step S12), and the suction time difference is increased (step S13). (Step S3).

  As described above, it is necessary to repeat the sheet suction operation several times to obtain the proper suction time, and there is a concern that it takes time until the sheet feeding starts.

  However, as shown in this example, the appropriate adsorption time difference and allowable height difference for the paper type, basis weight, and environmental information obtained in advance by experiments etc. are tabulated and referred to as a database to minimize repeated operations. Can be suppressed.

  In addition, since the appropriate adsorption time difference when the sheet is actually sucked is reflected and updated in the database, even if the appropriate value deviates due to variations in sheet feeding device performance or sheet lot differences, it can be quickly performed from the next operation. An appropriate value can be obtained.

  Next, the sheet continuous feeding mode will be described with reference to FIG. In this example, the height difference H is detected for each sheet suction and compared with the allowable height difference H0 (steps S21 to S23). The operation when H is less than H0 and the difference is 2 mm or less (steps S24 and S25) and when H is greater than H0 (steps S29 and S30) is the same as the operation at the initial stage of sheet feeding shown in FIG. is there. If the sheet is not the final sheet after step S25 (step S26), the process returns to (A).

  When H is equal to or less than H0 and the difference exceeds 2 mm, unlike the operation at the initial stage of sheet feeding, sheet conveyance is performed (step S27), and the suction time is changed to be small (step S28). See the effect on the next sheet.

  This is because wrinkles are not generated even if the sheet is conveyed as it is, and there is no problem. This is to prevent a decrease in productivity due to temporarily stopping the sheet conveyance.

  In this embodiment, the difference in height is detected for each sheet conveyance and the appropriate suction time is calculated. However, the detection may be performed at intervals for each of the plurality of sheets, or the initial time may be shortened to change the proper suction time. The detection interval may be made variable, for example, the detection interval may be widened when the frequency of.

  Thus, in the present embodiment, the suction time is optimized by detecting the height difference even during continuous sheet feeding. As a result, even if there is a change in physical properties due to a difference in the amount of moisture in the sheet bundle, or a change in the degree of undulation due to a change in physical properties between the sheet bundle left in the storage and the newly added sheet bundle, wrinkle generation is an opportunity. Suppressed in response.

  The embodiment of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiment, and the scope does not depart from the spirit of the invention described in the claims of the present invention. Thus, various changes can be made.

  In this embodiment, the suction ports are arranged side by side in the direction perpendicular to the transport direction. Without being limited thereto, in a feeding device that conveys a sheet in which undulations occur in the conveyance direction, a plurality of suction ports are arranged in the conveyance direction, and the suction timing is similarly shifted. The same wrinkle prevention effect as in this embodiment can be obtained.

  In this case, it is preferable that the upstream side is sucked first so that the downstream side in the conveyance direction of the sheet that is most likely to be affected by undulation is sucked last.

  Further, in this case, it is preferable that the undulation detection sensor 71 is disposed at a position where an end portion along the sheet conveyance direction is detected.

  Moreover, in this embodiment, although the magnitude | size of the undulation was optimized by the adsorption | suction time difference of several adsorption openings 54a, 54b, 54c, when the suction | attraction air volume to adsorb | suck is made small, it turns out that the magnitude | size of a undulation becomes small. .

  Therefore, instead of the adsorption time difference, the suction air volume may be varied to optimize the undulation. In this case, since a configuration with a single suction means (suction fan, suction solenoid, suction shutter) is possible, the cost and size of the apparatus can be reduced.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. It is a block diagram of the sheet feeding apparatus shown in FIG. FIG. 2 is a block diagram of the sheet feeding device in FIG. 1. (A)-(c) is a process figure which shows operation | movement of a sheet feeding apparatus. (A)-(c) is a state figure of a sheet | seat. FIG. 10 is an operation timing chart of the sheet feeding device. It is a undulation state diagram by a undulation detection sensor. It is the figure which showed the relationship between elevation difference and wrinkle incidence. It is a undulation state diagram by a undulation detection sensor. It is a flowchart of appropriate adsorption time difference acquisition mode. It is a flowchart of continuous feeding mode. It is a schematic sectional drawing of the conventional air sheet feeding apparatus. It is a schematic sectional drawing of the conventional air sheet feeding apparatus. It is a schematic sectional drawing of the conventional air sheet feeding apparatus. It is a schematic sectional drawing of the conventional air sheet feeding apparatus. It is a schematic sectional drawing of the conventional air sheet feeding apparatus.

Explanation of symbols

21 Conveyance suction belt
51-53 Adsorption shutter
54a, 54b, 54c Suction port
60a, 60b, 60c Conveying suction belt
61, 62 Paper detection sensor
70 Adsorption duct
71 Wave detection sensor
115 storage

Claims (8)

A sheet storing means for storing the sheet bundle, an air blowing means for blowing air to the sheet bundle stored in the sheet storing means, and an air adsorbing one by one from the uppermost sheet floated by the air blowing means In an image forming apparatus comprising:
It has a height difference detecting means for detecting a height difference of deformation generated in the uppermost sheet sucked by the suction conveying means, and the height difference detected by the height difference detecting means and the sheet are properly conveyed. The image forming apparatus is characterized in that the suction condition of the suction conveyance means is changed by comparing with an allowable height difference. The image forming apparatus according to claim 1, wherein the suction conveyance unit includes a plurality of suction units, and the change of the suction condition is performed by shifting a time for starting the suction of the plurality of suction units. . The image forming apparatus according to claim 2, wherein the plurality of suction units are arranged in a direction orthogonal to the sheet conveyance direction, and a central suction unit starts suction first. The image forming apparatus according to claim 2, wherein the plurality of suction units are arranged in the sheet conveyance direction, and the suction unit on the upstream side in the conveyance direction starts the suction first. 5. The image forming apparatus according to claim 2, wherein the change of the suction condition changes a shift amount of time for starting the suction of the plurality of suction portions. 6. The said adsorption | suction conveyance means has at least 1 or more adsorption | suction part, and the change of adsorption | suction conditions changes the suction | attraction air volume of the said adsorption | suction part, The any one of Claim 1 thru | or 5 characterized by the above-mentioned. Image forming apparatus. The image forming apparatus according to claim 1, wherein a suction condition is determined before feeding the sheet. 8. The image forming apparatus according to claim 1, wherein when the sheet is fed, the suction condition is changed according to the height difference detected by the height difference detecting unit.

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